Path helpers

[coatless]

The present structure is:

/grade                         # Root directory of the grading job
+-- /data                      # JSON dump of the data object from server.py
|   `-- data.json   
|
+-- /run                       # Working Directory directory 
|   +-- /testthat
|   |   +-- testfile           # Test framework configuration
|   |   `-- staff_answer.R     # Test framework configuration
|   +--studentfile1
|   `-- run.sh
|
+-- /results                   # Report of test output formatted for PrairieLearn
|   `-- results.json   
|
+-- /serverFilesCourse         # Files from serverFilesCourse/ in the course directory
|   +-- /my_testing_framework 
|   |   +-- testfile           # Test framework configuration
|   |   `-- run.sh             # Entrypoint called in the container
|
+-- /student                   # Files submitted by student
|   +-- studentfile1
|   `-- studentfile2
|
+-- /tests                     # Files found in the question's tests/ directory
|   +-- test1
|   `-- test2
|
+-- /...                       # Additional directories and files as needed.

Instead of typing...

"/grade/student/studentfile1.R"

Let's aim for:

pltest::path_student("studentfile1.R")

Path student would auto-resolve.